Description: This function lists the defined element sets in a pop-up window. The user can then select the current set from those listed.
Usage:
1. DSI prompts:
> SELECT SET FROM ELEMENT SET LIST
? [List of all element sets]
CURSOR AT ELEMENT
EXIT
2. Once the set is selected, DSI prompts:
> SET X IS SELECTED
> ELEMENT SET X FLAGGED AS CURRENT SET.